A beaker of water is heated to 50°C. Then an unidentified powder is mixed into the water. The powder gradually disappears. However, as the water cools, the powder collects again at the bottom of the beaker.
Do the observations show that a chemical reaction occurred between the powder and the water?
Select the correct words from the drop-down menus to complete the explanation.
The most likely explanation is that the powder
Choose... Changed state in/ Dissolved in/ Combined with
the warm water, which is an example of a
Choose... physical Chemical
change of matter. So, a chemical reaction
Choose... did/did not
occur.